When you run Makefile.PL, it makes a Makefile. That's the whole point of MakeMaker. The Makefile.PL is a simple module which loads ExtUtils::MakeMaker and runs the WriteMakefile() function with a few simple arguments.

A short description of your module, what it does, why someone would use it and its limitations. CPAN automatically pulls your README file out of the archive and makes it available to CPAN users, it is the first thing they will read to decide if your module is right for them.

A file full of regular expressions to exclude when using 'make manifest' to generate the MANIFEST. These regular expressions are checked against each filepath found in the distribution (so you're matching against "t/foo.t" not "foo.t").